This invention relates to a method to obtain slices of peeled fresh fruit flesh for consumer use, from fresh fruits with pith or similar difficulties and properly gauged and washed, together with a device used to obtain slices from whole pieces of fruit.
Large kitchens such as those now commonly known as xe2x80x9ccateringxe2x80x9d kitchens, or certain major consumers, such as prepared food establishments selling to the public, banquet rooms, large supermarkets, hospitals, schools etc., have been asking the food processing industry for a system to provide peeled fruit flesh cut in slices, ready for eating, and which can be kept physically stable for a somewhat longer time than foreseen, for its distribution, sale and consumption.
The food processing industry cannot provide a satisfactory device for certain fruits, such as those with very soft flesh or with pith. An example of this is the demand for the most popular fruit, which is orange slices. Consumers ask that these slices:
1.- have flesh that meets the physical integrity conditions (cellular, vesicular, etc.) that enable industrial sanitary processes to provide a life span of at least 10 days from preparation to the end consumer.
2.- that their mechanical aspect maintains a pleasant appearance, in their final presentation and that they are easy to eat using a knife and fork, and
3.- they are free of pith that gives them an undesirable bitter taste.
Peeled orange slices that are currently on the market are either peeled manually and the pith remains are carefully removed manually, or oranges are peeled mechanically and the pith remains are carefully removed mechanically. Both procedures end by mechanically slicing the resulting spherical flesh.
Clean flesh slices obtained manually meet the three previously mentioned conditions, but the costs involved in preparation are incompatible with the industrial processes. The manual process is very unpopular in the food processing industry.
Clean flesh slices obtained mechanically either have unwanted remains of pith, or if they are completely free of pith, the flesh is cut and the cellular and vesicular walls are broken.
Flesh with cuts and broken cells and vesicles does not meet condition 1, as cut and broken flesh means that a large volume of the fruit, and also the abundant dispersed juice, are exposed to a large extent, to bacteria, fungi and enzymes, against which current sanitary treatments are not effective. For example, the most common industrial sanitary treatment is to finally wash the fruit with an aqueous solution of sodium hypochlorite. This solution must be very diluted to prevent the fruit slice from having a taste of bleach. The very small amount of sodium hypochlorite used in the treatment means that its preventive properties are not effective when external agents have too many opportunities to proliferate, such as in this case. These fresh fruit flesh slices have a life span of two days, which is such a short period of time, that purely for logistic reasons, there could be a health risk of consuming the fruit past the sell-by date.
Also, this flesh is a long way from optimum mechanical appearance, it is soft and excessively flexible and does not meet condition 2.
In other fresh fruit slices, such as soft flesh fruit, when slices are prepared following usual industrial methods, there could be similar problems of appearance and sanitary treatment.
To solve all these problems, a method and device has been designed to obtain fresh fruit flesh slices, which is the purpose of this invention, that provides features directed at automatically preparing peeled fresh fruit slices with pith or with resembling peel, ensuring minimum damage in the vesicular walls where the juice is.
With this invention, the food processing industry is able to offer customers very clean and whole flesh slices of fruits with pith or similar difficulties that meet the three conditions indicated in the previous point. The method consists of a non-intuitive process that makes the slices of the fruit peeled instead of the fruit. In this way, the mechanical support of the peel is used to reduce damage to the flesh during the mechanisation of the process. Sanitary, mechanical and appearance qualities of the fresh peeled and clean flesh are improved to such an extent that they meet the aforementioned conditions satisfactorily.
The flesh remains the same or more integral than when peeling is done manually, because slicing fruit that has already been peeled, such as oranges, puts deforming pressure on an object that has lost the mechanical support of the peel, meaning that cuts and breakage of walls and membrane can occur, together with the dispersion of juice to a greater extent than when the fruit is sliced using this invention. With this method, fresh fruit flesh slices are obtained, in which the suitable aseptic treatment provides a life span of 12 days or more, which is considered acceptable to consumers.
With this invention, the fruit is sliced mechanically by positioning it manually in a two-conveyor belt system. Each of these conveyor belts has holes or optionally cells that are facing each other. The fruit is secured when its axial caps are inserted into these holes or cells. A cap is the end where the peduncle is located, and the other cap corresponds to the opposite apex. The relative position of the caps does not necessarily always have to be the same, simply the axis that joins them always has to be perpendicular to the planes of the belts.
The fruit is therefore positioned on the moving belt with holes. On the outer surface of each belt there is a blade that cuts the corresponding cap. The cap falls and is lead to its final position.
As long as it is the correct thickness, cutting the cap always guarantees that the pith is removed in this portion of the fruit, and therefore the ends remain free of pith and skin, of course.
The rest of the fruit continues to be held, as it is still secured in the holes. It is sliced by a set of blades. If the fruit is positioned between cells, all the blades are between the belts and the caps, and the slices will then be separated in a gauging belt. The next step has two options:
1.- The slices pass to another diameter gauging belt. In the case of oranges, three to five slices per fruit can be cut, as required. Therefore there will be two to three diameters to differentiate (without counting the caps if applicable). The slices, classified according to diameter, are led to peeling module units, The blades of each of these modules are adjusted to peel the slices according to their diameter.
2.- The slices are not differentiated by diameter and are led to a machine with a device that adjusts the blades to cut the slices held by the tongs.
Both options have a common star-shaped feeder that takes the slices from the belt one by one, and places each slice on top of open tongs. The tong arms are in constant circular movement, held to a power-driven revolving machine.
The axle is equipped with accessories that transform the rotary movement of the axle into another type of movement. Therefore, the tong arms continue to move closing and securing the slice of fruit.
The inner surface of the tongs is provided with anti-slip elements, for example two or three cantilevered cams at different levels. Without these elements, it would be difficult to hold a tapered slice, with a smaller diameter at the bottom, as the slice could slide upwards, slipping out of the tongs and causing a machining error. Resistance to vertical movement provided by the anti-slip elements stops slices from sliding upwards.
Without any physical contact, a mechanism moves over the tong, which has a piston alternately moving up and down. The origin of this movement is a rail bushing located on the upper end that moves over the periphery of a slanted disc. The pistons have springs for transmission during the downward vertical movement to the corresponding pushers that almost wrap around the pistons.
When the feeder places a slice of fruit between the open arms of the tongs, the piston is up. While the arms close, the piston lowers and once the tongs hold the slice, the flat end of the pusher presses against it, securing it and preventing it from rotating which it would do during the next step, if it were not secured.
Bordering the circular perimeter of the piston, and therefore the flat base of the pusher, a cutting blade quickly moves depending on the foreseen circumference for peeling. This movement is possible because the pistons have a cogwheel in the centre, that is kept geared by the fixed toothed plate, turning the pistons and consequently, the blades fixed on them, throughout the circular run of the pistons in the cutting module.
The aforementioned circulating blade lowers with the piston, reaching the slice when it is held by the tongs and the pusher. The blade peels the slice of fruit, cutting the flesh along the edge in contact with the pith. An essential parameter during this phase, is the synchronisation between the blade rotation and the movement of the fruit slice. To assist this synchronisation, a blade with a cutting angle lower than 45xc2x0, with a straight or concave edge should be used.
The slice of fruit flesh falls flat on a short distance conveyor belt and is led to its destination. The tongs open and the piston moves upwards. The open tongs drop the ring of peel and, if applicable, the pith in an appropriate place, such as another conveyor belt.
In the event that the ring of peel remains held to an arm of the tongs owing to an anti-slip element, and gravity is not sufficient to release the peel so that it falls, a separator bar is placed in the unloading area of the rings of peel. This bar is prismatic, and it has a right-angle triangle section. The bar is positioned so that one of its narrow sides (leg of the section) is in the upper position, parallel to the plane of the circular movement; the wider side (hypotenuse of the section) faces the vector of the circular movement; the angle opposite the aforementioned leg is in the lower position. This lower angle is positioned one or two millimetres above the upper surface of the tong arms, taking advantage of the fact that the height of these arms (from 5 to 8 mm) is always less than the height of the fruit slices (from 10 to 17 mm). As these project, the force vector produced when the ring of peel is released but has not fallen, collides against this slanted surface and unfolds into two components, the downward vector being the actuator forcing the ring of peel to fall.
The fruit flesh sliced in this way has been damaged as little as possible, and will therefore preserve its appearance and mechanical, nutritional and organoleptic qualities. Suitable hygienisation treatment will be sufficient to prolong its life span for twelve days or more, which is longer than what is currently required.
The two options given above are designed to cover the particular cases of manufacturers. In the first option, the slices are gauged by means of a chain belt that runs forming successive cavities that increase in width. The width of each cavity is adjusted to separate slices of a certain diameter, and the caps if present. In the narrowest cavity, which is the first of the series, the slices with the smallest diameter fall and are separated, or the caps if present. In the last cavity, the slices with a diameter before the largest, fall. The largest diameter slices do not fall into any cavity and reach the belt that feeds the corresponding slice peeler module, where the blades are ready to peel this diameter. The other gauged slices go to the corresponding conveyor belt and module.
The orange slices from the classifier unit are transported on a conveyor belt to a roller carriage, which forces them to fall vertically onto another conveyor belt. Owing to the tapered shape of the slices, they always slant towards the base with the smallest diameter. The slices then reach the slice turning machine formed by a system of belts and rollers that force them to turn on the base with the largest diameter, on a reception belt that feeds the peeler module.
In the peeler module of this option, the diameter of the circumference of the blade path is always fixed once the module is in operation. When convenient, this diameter can be modified by stopping the module and adjusting the corresponding mechanical elements to adapt the distance between the blade and the piston axle. Once this is done, the peeling diameter will once again be fixed.
A typical installation of this option is a system of conveyor belts, a system of slicing blades, a gauging belt, a slice turning machine, one to three peeling modules and the elements to transport the final products. It is possible to have one single module if the manufacturer wishes to peel slices of one size, stop the peeling module, readjust the path of the peeling blades and the horizontal circular support, over which the slices move, and then peel slices of the different size. There are less costs involved in this option, but more space is required (if all peeling modules are installed) or more handling (if one single module is installed).
If the second option is selected, the single peeling module has a mechanism that adjusts the circular path of the peeling blades for each slice of fruit. This mechanism is informed of the diameter of the slices entering by an artificial viewing system that detects characteristics, such as, in the case of oranges, a change in colour from the flesh (orange) to the pith (white). This information is used by the mechanism to adjust the path of the peeling blades, so that they cut the flesh right at the edge in contact the pith. By extending the radius of the circumference of the path of the tongs and piston, the time needed to correctly perform this operation is increased, maintaining the mechanical output of a slice of peeled fruit flesh per second.
Alternatively and for cases in which precision in peeling is not essential, the information of the diameter to which the peeling blades should adjust, could come from the tongs. When the arms of the tongs close, depending on the distance, they could already have the information regarding the adjustment of blades.
A typical installation of this option is a system of conveyor belts, a system of slicing blades, a slice turning machine, a peeling module and elements to transport the final products. Higher costs are involved in this option, but less space is required.